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Avoid costly 64-bit division in grub_get_time_ms on most platforms.

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This commit is contained in:
Vladimir 'phcoder' Serbinenko 2013-03-10 17:45:38 +01:00
parent fc3ff2a2ad
commit 5341c0fbfc
10 changed files with 70 additions and 93 deletions
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4
ChangeLog
View file

@ -1,3 +1,7 @@
2013-03-10 Vladimir Serbinenko <phcoder@gmail.com>
Avoid costly 64-bit division in grub_get_time_ms on most platforms.
2013-03-10 Vladimir Serbinenko <phcoder@gmail.com>
* grub-core/fs/fshelp.c (grub_fshelp_log2blksize): Remove now unused

14
grub-core/Makefile.am
View file

@ -98,29 +98,29 @@ if COND_i386_pc
KERNEL_HEADER_FILES += $(top_builddir)/include/grub/machine/kernel.h
KERNEL_HEADER_FILES += $(top_builddir)/include/grub/machine/pxe.h
KERNEL_HEADER_FILES += $(top_builddir)/include/grub/machine/int.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
endif
if COND_i386_efi
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/efi.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/disk.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/pci.h
endif
if COND_i386_coreboot
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
KERNEL_HEADER_FILES += $(top_builddir)/include/grub/i386/pc/int.h
endif
if COND_i386_multiboot
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
KERNEL_HEADER_FILES += $(top_builddir)/include/grub/i386/pc/int.h
endif
if COND_i386_qemu
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/pci.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
endif
if COND_i386_ieee1275
@ -128,13 +128,13 @@ KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/ieee1275/ieee1275.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/terminfo.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/extcmd.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/lib/arg.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
endif
if COND_x86_64_efi
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/efi.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/disk.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/pci.h
endif

3
grub-core/Makefile.core.def
View file

@ -102,7 +102,6 @@ kernel = {
noemu_nodist = symlist.c;
i386_pc = kern/generic/rtc_get_time_ms.c;
mips = kern/generic/rtc_get_time_ms.c;
ieee1275 = disk/ieee1275/ofdisk.c;
@ -123,8 +122,6 @@ kernel = {
i386_coreboot_multiboot_qemu = kern/i386/coreboot/init.c;
i386_coreboot_multiboot_qemu = term/i386/pc/vga_text.c;
x86 = kern/i386/pit.c;
efi = disk/efi/efidisk.c;
efi = kern/efi/efi.c;
efi = kern/efi/init.c;

6
grub-core/kern/i386/pc/init.c
View file

@ -52,8 +52,8 @@ void (*grub_pc_net_config) (char **device, char **path);
* return the real time in ticks, of which there are about
* 18-20 per second
*/
grub_uint32_t
grub_get_rtc (void)
grub_uint64_t
grub_rtc_get_time_ms (void)
{
struct grub_bios_int_registers regs;
@ -61,7 +61,7 @@ grub_get_rtc (void)
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x1a, &regs);
return (regs.ecx << 16) | (regs.edx & 0xffff);
return ((regs.ecx << 16) | (regs.edx & 0xffff)) * 55ULL;
}
void

49
grub-core/kern/i386/pit.c
View file

@ -1,49 +0,0 @@
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2008 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/types.h>
#include <grub/i386/io.h>
#include <grub/i386/pit.h>
void
grub_pit_wait (grub_uint16_t tics)
{
/* Disable timer2 gate and speaker. */
grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
& ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
GRUB_PIT_SPEAKER_PORT);
/* Set tics. */
grub_outb (GRUB_PIT_CTRL_SELECT_2 | GRUB_PIT_CTRL_READLOAD_WORD,
GRUB_PIT_CTRL);
grub_outb (tics & 0xff, GRUB_PIT_COUNTER_2);
grub_outb (tics >> 8, GRUB_PIT_COUNTER_2);
/* Enable timer2 gate, keep speaker disabled. */
grub_outb ((grub_inb (GRUB_PIT_SPEAKER_PORT) & ~ GRUB_PIT_SPK_DATA)
| GRUB_PIT_SPK_TMR2,
GRUB_PIT_SPEAKER_PORT);
/* Wait. */
while ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH) == 0x00);
/* Disable timer2 gate and speaker. */
grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
& ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
GRUB_PIT_SPEAKER_PORT);
}

50
grub-core/kern/i386/tsc.c
View file

@ -25,37 +25,66 @@
#include <grub/misc.h>
#include <grub/i386/tsc.h>
#include <grub/i386/pit.h>
#include <grub/cpu/io.h>
/* This defines the value TSC had at the epoch (that is, when we calibrated it). */
static grub_uint64_t tsc_boot_time;
/* Calibrated TSC rate. (In TSC ticks per millisecond.) */
static grub_uint64_t tsc_ticks_per_ms;
/* Calibrated TSC rate. (In ms per 2^32 ticks) */
/* We assume that the tick is less than 1 ms and hence this value fits
in 32-bit. */
grub_uint32_t grub_tsc_rate;
static void
grub_pit_wait (grub_uint16_t tics)
{
/* Disable timer2 gate and speaker. */
grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
& ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
GRUB_PIT_SPEAKER_PORT);
/* Set tics. */
grub_outb (GRUB_PIT_CTRL_SELECT_2 | GRUB_PIT_CTRL_READLOAD_WORD,
GRUB_PIT_CTRL);
grub_outb (tics & 0xff, GRUB_PIT_COUNTER_2);
grub_outb (tics >> 8, GRUB_PIT_COUNTER_2);
/* Enable timer2 gate, keep speaker disabled. */
grub_outb ((grub_inb (GRUB_PIT_SPEAKER_PORT) & ~ GRUB_PIT_SPK_DATA)
| GRUB_PIT_SPK_TMR2,
GRUB_PIT_SPEAKER_PORT);
/* Wait. */
while ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH) == 0x00);
/* Disable timer2 gate and speaker. */
grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
& ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
GRUB_PIT_SPEAKER_PORT);
}
grub_uint64_t
grub_tsc_get_time_ms (void)
{
return tsc_boot_time + grub_divmod64 (grub_get_tsc (), tsc_ticks_per_ms, 0);
grub_uint64_t a = grub_get_tsc () - tsc_boot_time;
grub_uint64_t ah = a >> 32;
grub_uint64_t al = a & 0xffffffff;
return ((al * grub_tsc_rate) >> 32) + ah * grub_tsc_rate;
}
/* How many RTC ticks to use for calibration loop. (>= 1) */
#define CALIBRATION_TICKS 2
/* Calibrate the TSC based on the RTC. */
static void
calibrate_tsc (void)
{
/* First calibrate the TSC rate (relative, not absolute time). */
grub_uint64_t start_tsc;
grub_uint64_t end_tsc;
start_tsc = grub_get_tsc ();
tsc_boot_time = grub_get_tsc ();
grub_pit_wait (0xffff);
end_tsc = grub_get_tsc ();
tsc_ticks_per_ms = grub_divmod64 (end_tsc - start_tsc, 55, 0);
grub_tsc_rate = grub_divmod64 ((55ULL << 32), end_tsc - tsc_boot_time, 0);
}
void
@ -63,7 +92,6 @@ grub_tsc_init (void)
{
if (grub_cpu_is_tsc_supported ())
{
tsc_boot_time = grub_get_tsc ();
calibrate_tsc ();
grub_install_get_time_ms (grub_tsc_get_time_ms);
}

28
grub-core/loader/i386/xnu.c
View file

@ -125,9 +125,6 @@ guessfsb (void)
{
const grub_uint64_t sane_value = 100000000;
grub_uint32_t manufacturer[3], max_cpuid, capabilities, msrlow;
grub_uint64_t start_tsc;
grub_uint64_t end_tsc;
grub_uint64_t tsc_ticks_per_ms;
if (! grub_cpu_is_cpuid_supported ())
return sane_value;
@ -192,14 +189,6 @@ guessfsb (void)
if (! (capabilities & (1 << 7)))
return sane_value;
/* Calibrate the TSC rate. */
start_tsc = grub_get_tsc ();
grub_pit_wait (0xffff);
end_tsc = grub_get_tsc ();
tsc_ticks_per_ms = grub_divmod64 (end_tsc - start_tsc, 55, 0);
/* Read the multiplier. */
asm volatile ("movl $0x198, %%ecx\n"
"rdmsr"
@ -207,8 +196,21 @@ guessfsb (void)
:
: "%ecx", "%eax");
return grub_divmod64 (2000 * tsc_ticks_per_ms,
((msrlow >> 7) & 0x3e) + ((msrlow >> 14) & 1), 0);
grub_uint64_t v;
grub_uint32_t r;
/* (2000ULL << 32) / grub_tsc_rate */
/* Assumption: TSC frequency is over 2 MHz. */
v = 0xffffffff / grub_tsc_rate;
v *= 2000;
/* v is at most 2000 off from (2000ULL << 32) / grub_tsc_rate.
Since grub_tsc_rate < 2^32/2^11=2^21, so no overflow.
*/
r = (2000ULL << 32) - v * grub_tsc_rate;
v += r / grub_tsc_rate;
return grub_divmod64 (v, ((msrlow >> 7) & 0x3e) | ((msrlow >> 14) & 1),
0);
}
struct property_descriptor

5
include/grub/i386/pc/time.h
View file

@ -21,9 +21,4 @@
#include <grub/symbol.h>
#define GRUB_TICKS_PER_SECOND 18
/* Return the real time in ticks. */
grub_uint32_t grub_get_rtc (void);
#endif /* ! KERNEL_MACHINE_TIME_HEADER */

2
include/grub/i386/pit.h
View file

@ -100,6 +100,4 @@ enum
GRUB_PIT_CTRL_COUNT_BCD = 0x01 /* 4-decade BCD counter. */
};
void EXPORT_FUNC(grub_pit_wait) (grub_uint16_t tics);
#endif /* ! KERNEL_CPU_PIT_HEADER */

2
include/grub/i386/tsc.h
View file

@ -137,5 +137,7 @@ grub_cpu_is_tsc_supported (void)
void grub_tsc_init (void);
grub_uint64_t grub_tsc_get_time_ms (void);
/* In ms per 2^32 ticks. */
extern grub_uint32_t EXPORT_VAR(grub_tsc_rate);
#endif /* ! KERNEL_CPU_TSC_HEADER */